Naturally,resistant crop germplasms are important resources for managing the issues of agricultural product safety and environment deterioration.We found a spontaneous mutant of‘Newhall’navel orange(Citrus sinensis ...Naturally,resistant crop germplasms are important resources for managing the issues of agricultural product safety and environment deterioration.We found a spontaneous mutant of‘Newhall’navel orange(Citrus sinensis Osbeck)(MT)with broad-spectrum protections against fungal pathogens in the orchard,postharvest-storage,and artificial inoculation conditions.To understand the defense mechanism of MT fruit,we constructed a genome-scale metabolic network that integrated metabolome and transcriptome datasets.The coordinated transcriptomic and metabolic data were enriched in two sub-networks,showing the decrease in very long chain fatty acid(by 41.53%)and cuticular wax synthesis(by 81.34%),and increase in the synthesis of jasmonic acid(JA)(by 95.23%)and JA-induced metabolites such as 5-dimethylnobietin(by 28.37%)in MT.Furthermore,cytological and biochemical analyses confirmed that the response to fungal infection in MT was independent of wax deficiency and was correlated with the levels of jasmonates,and the expression of plant defensin gene PDF1.2.Results of exogenous application of MeJA and JA inhibitors such as propyl gallate proved that JA-mediated defense contributes to the strong tolerance against pathogens in MT.Our results indicated that jasmonate biosynthesis and signaling are stimulated by the fatty acid redirection of MT,and participate in the tolerance of pathogenic fungi.展开更多
Elaioplasts of citrus peel are colorless plastids which accumulate significant amounts of terpenes.However,other functions of elaioplasts have not been fully characterized to date.Here,a LC–MS/MS shotgun technology w...Elaioplasts of citrus peel are colorless plastids which accumulate significant amounts of terpenes.However,other functions of elaioplasts have not been fully characterized to date.Here,a LC–MS/MS shotgun technology was applied to identify the proteins from elaioplasts that were highly purified from young fruit peel of kumquat.A total of 655 putative plastid proteins were identified from elaioplasts according to sequence homology in silico and manual curation.Based on functional classification via Mapman,~50%of the identified proteins fall into six categories,including protein metabolism,transport,and lipid metabolism.Of note,elaioplasts contained ATP synthase and ADP,ATP carrier proteins at high abundance,indicating important roles for ATP generation and transport in elaioplast biogenesis.Additionally,a comparison of proteins between citrus chromoplast and elaioplast proteomes suggest a high level of functional conservation.However,some distinctive protein profiles were also observed in both types of plastids notably for isoprene biosynthesis in elaioplasts,and carotenoid metabolism in chromoplasts.In conclusion,this comprehensive proteomic study provides new insights into the major metabolic pathways and unique characteristics of elaioplasts and chromoplasts in citrus fruit.展开更多
Mandarin （Citrus reticulata） is one of the most important citrus crops worldwide. Its domestication is believed to have occurred in South China, which has been one of the centers of mandarin cultivation for four mil...Mandarin （Citrus reticulata） is one of the most important citrus crops worldwide. Its domestication is believed to have occurred in South China, which has been one of the centers of mandarin cultivation for four millennia. We collected natural wild populations of mandarin around the Nanling region and cultivated landraces in the vicinity. We found that the citric acid level was dramatically reduced in cultivated mandarins. To understand genetic basis of mandarin domestication, we de novo assembled a draft genome of wild mandarin and analyzed a set of 104 citrus genomes. We found that the Mangshan mandarin is a primitive type and that two independent domestication events have occurred, resulting in two groups of cultivated mandarins （MD1 and MD2） in the North and South Nanling Mountains, respectively. Two bottlenecks and two expansions of effective population size were identified for the MD1 group of cultivated mandarins. However, in the MD2 group there was a long and continuous decrease in the population size. MD1 and MD2 mandarins showed different patterns of interspecific introgression from cultivated pummelo species. We identified a region of high divergence in an aconitate hydratase （ACO） gene involved in the regulation of citrate content, which was possibly under selection during the domestication of mandarin. This study provides concrete genetic evidence for the geographical origin of extant wild mandarin populations and sheds light on the domestication and evolutionary history of mandarin.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.31772368,31572176,and 31521092)the National Modern Agriculture(Citrus)Technology Systems of China(No.CARS-27)the National Science&Technology Pillar Program of China(2015BAD16B06).
文摘Naturally,resistant crop germplasms are important resources for managing the issues of agricultural product safety and environment deterioration.We found a spontaneous mutant of‘Newhall’navel orange(Citrus sinensis Osbeck)(MT)with broad-spectrum protections against fungal pathogens in the orchard,postharvest-storage,and artificial inoculation conditions.To understand the defense mechanism of MT fruit,we constructed a genome-scale metabolic network that integrated metabolome and transcriptome datasets.The coordinated transcriptomic and metabolic data were enriched in two sub-networks,showing the decrease in very long chain fatty acid(by 41.53%)and cuticular wax synthesis(by 81.34%),and increase in the synthesis of jasmonic acid(JA)(by 95.23%)and JA-induced metabolites such as 5-dimethylnobietin(by 28.37%)in MT.Furthermore,cytological and biochemical analyses confirmed that the response to fungal infection in MT was independent of wax deficiency and was correlated with the levels of jasmonates,and the expression of plant defensin gene PDF1.2.Results of exogenous application of MeJA and JA inhibitors such as propyl gallate proved that JA-mediated defense contributes to the strong tolerance against pathogens in MT.Our results indicated that jasmonate biosynthesis and signaling are stimulated by the fatty acid redirection of MT,and participate in the tolerance of pathogenic fungi.
基金This work was supported by the National Natural Science Foundation of China(NSFC,grant nos.31501739)the National Basic Research Program of China(973 project No.2013CB127105)Huazhong Agricultural University Scientific&Technological Self-innovation Foundation(No.2662015BQ034).
文摘Elaioplasts of citrus peel are colorless plastids which accumulate significant amounts of terpenes.However,other functions of elaioplasts have not been fully characterized to date.Here,a LC–MS/MS shotgun technology was applied to identify the proteins from elaioplasts that were highly purified from young fruit peel of kumquat.A total of 655 putative plastid proteins were identified from elaioplasts according to sequence homology in silico and manual curation.Based on functional classification via Mapman,~50%of the identified proteins fall into six categories,including protein metabolism,transport,and lipid metabolism.Of note,elaioplasts contained ATP synthase and ADP,ATP carrier proteins at high abundance,indicating important roles for ATP generation and transport in elaioplast biogenesis.Additionally,a comparison of proteins between citrus chromoplast and elaioplast proteomes suggest a high level of functional conservation.However,some distinctive protein profiles were also observed in both types of plastids notably for isoprene biosynthesis in elaioplasts,and carotenoid metabolism in chromoplasts.In conclusion,this comprehensive proteomic study provides new insights into the major metabolic pathways and unique characteristics of elaioplasts and chromoplasts in citrus fruit.
基金This project was supported by the fundamental research funds for the central universities （2662015PY109）, and the National Natural Science Foundation of China （31572105, 31330066, and 31521092 to Q.X. and X.D.）.
文摘Mandarin （Citrus reticulata） is one of the most important citrus crops worldwide. Its domestication is believed to have occurred in South China, which has been one of the centers of mandarin cultivation for four millennia. We collected natural wild populations of mandarin around the Nanling region and cultivated landraces in the vicinity. We found that the citric acid level was dramatically reduced in cultivated mandarins. To understand genetic basis of mandarin domestication, we de novo assembled a draft genome of wild mandarin and analyzed a set of 104 citrus genomes. We found that the Mangshan mandarin is a primitive type and that two independent domestication events have occurred, resulting in two groups of cultivated mandarins （MD1 and MD2） in the North and South Nanling Mountains, respectively. Two bottlenecks and two expansions of effective population size were identified for the MD1 group of cultivated mandarins. However, in the MD2 group there was a long and continuous decrease in the population size. MD1 and MD2 mandarins showed different patterns of interspecific introgression from cultivated pummelo species. We identified a region of high divergence in an aconitate hydratase （ACO） gene involved in the regulation of citrate content, which was possibly under selection during the domestication of mandarin. This study provides concrete genetic evidence for the geographical origin of extant wild mandarin populations and sheds light on the domestication and evolutionary history of mandarin.
